Many home gardeners believe they need to top dress their lawn. Do you need to do this ? . Well it comes down to a number of factors, and in some cases it is required. The major reason you would want to top dress your lawn is to fill dips and level the lawn surface.This is the best reason to top dress and will improve the lawn in the long run. However, there is no need to top dress otherwise. Top dressing a lawn that does not need it can actually create more problems. Top dressing a lawn that does not need levelling will only create a deeper thatch layer (layer of roots) which reduces the vigour of your lawn. It will also benefit weeds, as the open soil will allow weeds to get established.